Objective: The aim of this study is to investigate the frequency of abnormal EEG findings in first attack mania and to determine whether EEG abnormality improves at the subsequent remission period. The secondary, to compare cases with or without abnormal EEG findings with regard to clinical characteristics of bipolar disorder in remission period. Methods: In the present study, 86 consecutive first episode mania cases between the ages of 18-65 diagnosed as Bipolar Disorder according to DSM-IV who referred to our outpatient clinic or emergency service whose informed consent form was signed by first degree relatives were evaluated. Inclusion criteria were not having previous depressive episode absence of any neurologic disorder, especially epilepsy, absence of history head trauma and/or loss of consciousness and not using any drugs which can influence electroencephalographic activity before EEG (antiepileptic, anxiolytic, antidepressant and antipsychotics) diagnostic interviews were made with SCID-I (DSM-IV Structured Clinical Interview) and information on disease was recorded with SKIP-TURK (Mood Disorder Diagnosis and Follow up Form). EEG recordings were made with digital EEG device in 16 channels. Results: EEG abnormality is more frequent in mania than remission period (p= 0.022). All cases with continuing abnormal EEG findings in remission period are women. In cases with continuing EEG abnormality, the age of menarche is smaller (p= 0.032) but family history is less frequent (p= 0.008). Childhood trauma and history of suicide attempt is more frequent in cases with persistent EEG abnormality in remission period as well (p= 0.001 and 0.005). Of the cases whose abnormal EEG findings improved in remission period, 83.3% were treated with anticonvulsants. Conclusion: In some bipolar cases, abnormal EEG is present from the onset of disease and is associated with clinical characteristics. Abnormal EEG returns to normal in half of the cases in remission period. [Anadolu Psikiyatri Derg 2014; 15(1.000): 1-7]